Safety device for steam-boilers.



PATENTE) 0011.22, 19017.

C. LETTERI. SAFETY DEVICE FOR STEAM BOI-LEES.

Swann/Lto@ I n l Ifl ' .APPLICATIONl FILED APR. 24.1907.

` 1 l n" ni\\\\\\\\\\II\`\ CHARLES LETTERI, OF COLUMBUS, OHIO.

SAFETY DEVICE FOR STEAM-BOILERS.

Specification of Letters Patent.

:Patented Oct. 22, 1907.

Application filed April 24,1907. Serial No. 369,938.

To all. 'whom it may concern:

Be it known that I, CHARLES LETTEni, a citizen oi the United States, residing at Columbus, in the county oi Franklin and State of Ohio, have invented a certain new and useiul Improvement in SaetyDevices for Steam-Boilers, oi which the following is a specification.

The object of this invention is to provide improved means for preventing the explosion of steam boilers due to the exposure of the crown-plate to the direct heat oi the Iire when, through the carelessness of the operator or through unavoidable circumstances, the water in the boiler has become dangerously low. It is a well-known iact that the greater number of boiler explosions are due to the weakening of the crownplate under the conditions referred to, the plate becoming softened and caused to sag and break under the pressure of the steam.

The invention consists brieiiy in the provision oi means, in connection with the crown-plate or other part of the boiler shell between the steam and combustion chambers, adapted to be weakened and collapsed under exposure oi the direct heat oi the fire thereon prior to the lowering of the water so as to expose the crown-sheet. The rupture and collapsing oi the device permits the liberation oi the steam, whereby the pressure in the boiler is not only relieved but the liberated steam is directed upon the fire and deadens the same.

Embodiments oi the invention are shown in the accompanying drawings, but the invention is not limited to the precise construction and arrangement shown.

In said drawings-Figure l is a sectional view of a portion oi a locomotive boiler showing the application ol the invention thereto; Fig. 2 is a sectional view on an enlarged scale showing portions of a crown- )late and root-plate with crown-bolts and the safety device applied; Fig. 3 is a similar view showing a modilied form of the safety device, and Fig. 4 is a bottom plan view oi' a section of the crown-sheet with the safety device and crown -bolts applied.

In the several views l designates the crown-sheet of a steam boiler and 2 the roof or other companion sheet. These sheets are connected as usual by crown-bolts 3, 3. The safety devices are also located between the crown and top sheets and comprise in the instance shown in Fig. l a hollow stem 4 threaded into the top sheet and more firmly held against longitudinal movement or displacement by means oi a plug 5 driven into the end oi the stem.

6 designates a bell or cup-shaped coupling fitted snugly into an opening in the crown-sheet and connected by means of iine threads 6 with the stem 4. A bead or flange is also provided on the bell-shaped fiange to prevent the device from pullingr through the crown-plate. It is apparent that the part 6 can be threaded into the crown-sheet but the manner of attachment shown is preferred. The top oi the coupling G adjacent the threads, as indicated at 6b, is considerably thinner than the sides.

The purpose of the device is to relieve the steam pressure before the crown-sheet has been damaged and to provide a quick-acting safety device. It will be seen that both the coupling and the tube are open to the direct heat from the lire, but so long as the coupling and the lower lend oi the tube are covered with water they will remain unaffected by the heat of the fire. However, the instant they are uncovered and subjected to the steam pressure and the action oi the intense heat the pressure of the steam will collapse the coupling and tend to blow it out into the iire. The heat of the fire and the steam pressure also tend to reduce or elongate the lower end of the tube and loosen the connection, so that when the steam pressure is exerted on the top of the coupling the portion of the coupling engaging the stem is forced downward by reason of the thin portion of the coupling and, even if the coupling should not be blown out of the opening in the crown-plate, the parts will be disengaged and an opening had through which the steam will pass into the fire box. It is obvious that this rupture of the parts would take place while there was still water on the crown-sheet but at the time the water had become dangerously low.

It will be seen that the device not only effects the release oi the pressure in the boiler but the escaping steam is also directed upon the hre in the fire box and deadens the same. The escaping steam would necessarily have considerable iorce and would thus scatter and partly, if not wholly, extinguish the fire and thus remove liability of further injury to the boiler.

In the modiiication of the device shown in Fig. 3 the tube 7 is closed at its upper end and the bell-shaped coupling 8 is beaded at Sa and 8b on both sides oi the crown-sheet. In this construction the softening oi the parts and the pressure of the steam alone are relied upon to collapse the structure and cause the severance oi the parts 7 `and 8 at their threaded junction.

What I claim and desire to secure by Letters Patent is:

1. A steam boiler havingan opening in its shell between the steam and combustion chambers, a closure for said openingl located within the boiler and secured to the shell at said opening; and to a rigid part of the shell removed from the combustion chamber, said closure adapted to be ruptured when subjected to abnormal heat due to the lowering of the water in the steam chamber.

A steam boiler having an opening in its shell between the steam and combustion chambers, a hollow closure for said opening located within the boiler and comprising a cup-shaped portion secured to the shell at the opening and a tubular portion connected with a rigid part of the shell removed from the combustion chamber, said closure adapted to be ruptured when subjected to abnormal heut due t0 the lowering of the water in the steam chamber.

3. A steam boiler having an opening in its shell between the steam and combustion chambers, a hollow closure for said opening located within the boiler and comprising a cupshaped portion secured to the shell at the openingand a portion connected with a rigid part of the shell removed from the combustion chamber, said cupshaped part being provided with u thin or reduced portion adapted to be ruptured when the cup-shaped portion is subjected to abnormal heat due to the lowering of the Water in the stoom chamber.

CHARLES LETTERI. Witnesses z NATHANIEL G. WARNI, ALICE B. Comi. 

